VCE Biology Question Thread

[heids]

I'm fairly certain (not 100%) that's also in the scope of VCE bio. You should know about guard cells. Perhaps, just to confirm, hopefully someone else can answer this. Yet again, there's no harm in knowing 

There's nowhere in the SD about this - it really doesn't fit anywhere, old SD.  There WAS a question about it last year's exam methinketh, but from memory you didn't have to know how it worked, you just had to read and think carefully what was going on based on your knowledge of the stimulus-response model.

Hmm, 'there's no harm in knowing' is true-ish.  Knowing more is always great; it's just nice to know more, it expands your brain, it may make it easier to tackle a couple of questions etc. etc.  But I reckon, comparing myself with other people with slightly lower scores, that I learnt much less than them.  I figured out what the minimum was I could learn, and focused on maximising that - learning tangential stuff is more interesting but takes time away from the important stuff that ultimately wins you more marks, thus increasing your stress levels.  The rest you can often fill in by deduction or making stuff up.  Promise.
(Funny really, since I love learning stuff.  I just knew I had a limited amount of brain-space and time I had to maximise.)

10. do we have to know about this in VCE?  No, though you obviously have to know that oxygen concentration is important.

11. I know what happens during the ETC in cellular respiration, but do we need to know about cytochromes also? And what happens in ETC in photosynthesis that we need to know? Yes cytochromes.  No, don't need to know about ETC in photosynthesis at all - just know it's a thing.

12. can you answer my question for it? so does that mean quaternary enzymes have multiple active sites, and can bind to  more than one substrate? (is this for VCE level though?, because we define enzymes as only complementary to it's specific substrate, not substrates Don't know, very probably though.  You'll never be asked on an exam.  Note, that we do define enzymes as complementary to substrates, because in an anabolic reaction, there have to be multiple substrates to form a single product.

[cosine]

There's nowhere in the SD about this - it really doesn't fit anywhere, old SD.  There WAS a question about it last year's exam methinketh, but from memory you didn't have to know how it worked, you just had to read and think carefully what was going on based on your knowledge of the stimulus-response model.

Hmm, 'there's no harm in knowing' is true-ish.  Knowing more is always great; it's just nice to know more, it expands your brain, it may make it easier to tackle a couple of questions etc. etc.  But I reckon, comparing myself with other people with slightly lower scores, that I learnt much less than them.  I figured out what the minimum was I could learn, and focused on maximising that - learning tangential stuff is more interesting but takes time away from the important stuff that ultimately wins you more marks, thus increasing your stress levels.  The rest you can often fill in by deduction or making stuff up.  Promise.
(Funny really, since I love learning stuff.  I just knew I had a limited amount of brain-space and time I had to maximise.)

Hey bangali_lok

Cheers for the response. Oxygen is a product of photosynthesis, not an input so how can it's concentration affect the rate of photosynthesis?

[cosine]

I cannot believe i just got this question wrong:

Lipids are:
A. used an energy source
B. Involved in active transport
C. Part of glycoproteins
D. Transported by ER

How is the answer A? Can you give me a basic example please?

[pi]

One of the main functions of lipids is to be an energy store. Other main functions you should know include being a key component of cell walls, and being involved in various cell signalling.

[cosine]

One of the main functions of lipids is to be an energy store. Other main functions you should know include being a key component of cell walls, and being involved in various cell signalling.

Sorry I was not clear, I meant an example of it being an energy source xD

[sunshine98]

Oxygen is a product of photosynthesis, not an input so how can it's concentration affect the rate of photosynthesis?

Copy pasted this from my textbook
 ''Although oxygen is not involved directly in photosynthesis, in C3 plants net carbon dioxide fixation is reduced in the presence of oxygen . Therefore, reducing oxygen in the controlled atmosphere of a greenhouse will result in a considerable increase in photosynthesis''
However, I do think this is from the old study design (because C3 plants and stuff was in old study design) and you probably  wont need it. Which year is this question from ?

[heids]

Sorry I was not clear, I meant an example of it being an energy source xD

Well, stored fat like triglycerides in our adipose tissue.  When there's no polysaccharides/glucose available, it's metabolised into something (I totally don't remember any details) and somehow produces ATP.  Someone fill in on this, you don't need to know how, but as they store energy, they're obviously a source of energy.

Hey bangali_lok

Cheers for the response. Oxygen is a product of photosynthesis, not an input so how can it's concentration affect the rate of photosynthesis?

I should learn to think as I type.  Apologies.  Increased oxygen concentration shows/results from higher rates of photosynthesis, it doesn't affect the rate (as far as you need to know at VCE level in this study design).

[cosine]

Copy pasted this from my textbook
 ''Although oxygen is not involved directly in photosynthesis, in C3 plants net carbon dioxide fixation is reduced in the presence of oxygen . Therefore, reducing oxygen in the controlled atmosphere of a greenhouse will result in a considerable increase in photosynthesis''
However, I do think this is from the old study design (because C3 plants and stuff was in old study design) and you probably  wont need it. Which year is this question from ?

Yah it was 2011 chemology

Well, stored fat like triglycerides in our adipose tissue.  When there's no polysaccharides/glucose available, it's metabolised into something (I totally don't remember any details) and somehow produces ATP.  Someone fill in on this, you don't need to know how, but as they store energy, they're obviously a source of energy.
I should learn to think as I type.  Apologies.  Increased oxygen concentration shows/results from higher rates of photosynthesis, it doesn't affect the rate (as far as you need to know at VCE level in this study design).

Oh yah that's true, when theres no glycogen left stored in the liver and muscles, lipids start to get broken down into their respective sub units and converted to ATP. So is it a source of energy, or is it a energy storage? Or are they the same thing?

Haha you got me worried about the oxygen thing, all good xD

[pi]

Well, stored fat like triglycerides in our adipose tissue.  When there's no polysaccharides/glucose available, it's metabolised into something (I totally don't remember any details) and somehow produces ATP.  Someone fill in on this, you don't need to know how, but as they store energy, they're obviously a source of energy.

Fatty acids are converted into acetyl-CoA, the rest is fairly obvious. They store energy in their bonds, probably worth knowing this in a general sense.

So is it a source of energy, or is it a energy storage? Or are they the same thing?

When energy is needed, it's a source of energy. When energy is not needed, it's a store. Depends on the situation.

[Jay.C]

Hey guys just a bit confused on what to write in my summary for this part of the study design:
– dihybrid crosses as independent or linked
– pedigree analysis: autosomal and sex-linked inheritance; use of the test cross.

Would it be sufficient to describe each of the features in; Autosomal recessive, Autosomal dominant, X-linked domainant and X-linked recessive and then write about the test cross?

Or have I got it totally wrong?

[vox nihili]

Hey bangali_lok

Cheers for the response. Oxygen is a product of photosynthesis, not an input so how can it's concentration affect the rate of photosynthesis?

Still seems to be a bit of confusion about this one. The reason that high levels of oxygen reduce the rate of photosynthesis are complex, if you're not doing chemistry. Basically though, reactions slow down if the product of that reaction is abundant. So the end product of photosynthesis is oxygen, if there's lots of it around, photosynthesis will go more slowly because it doesn't need to produce more oxygen; because it's already there.

This isn't a biological thing, but more a chemistry thing. Basically though, there is a tendency for reactions to be favoured (i.e. occur) if the level of product of that reaction is low. Therefore, when there's lots of oxygen (i.e. the product) photosynthesis (i.e. the reaction) will not occur as frequently.

[cosine]

Still seems to be a bit of confusion about this one. The reason that high levels of oxygen reduce the rate of photosynthesis are complex, if you're not doing chemistry. Basically though, reactions slow down if the product of that reaction is abundant. So the end product of photosynthesis is oxygen, if there's lots of it around, photosynthesis will go more slowly because it doesn't need to produce more oxygen; because it's already there.

This isn't a biological thing, but more a chemistry thing. Basically though, there is a tendency for reactions to be favoured (i.e. occur) if the level of product of that reaction is low. Therefore, when there's lots of oxygen (i.e. the product) photosynthesis (i.e. the reaction) will not occur as frequently.

Thanks Mr. T-Rav for the highly sophisticated Uni explanation xD
Please tell me this would never appear on a VCE Bio exam (although it did on one of the practice chemology ones)

[pi]

Thanks Mr. T-Rav for the highly sophisticated Uni explanation xD
Please tell me this would never appear on a VCE Bio exam (although it did on one of the practice chemology ones)

Never say never, interpretation of study design is varied. Always good to read more into topics rather than less.

[cosine]

Okay cheers guys

Refering to rational drug design, are the drugs only being designed for pathogenic agents? Like for example, can biologists/chemists make drugs that inhibit certain enzymes? Is this an example of rational drug design? Also what about when someone has pain, can drugs be taken to like either act like enzymes and break down the neurotransmitters whilst diffusing through the synaptic cleft, or like bind on the post synaptic membrane receptors and block neurotransmitters from binding, hence no action potential is triggered to the adjacent neurone?

I feel like a doctor

[mahler004]

Okay cheers guys

Refering to rational drug design, are the drugs only being designed for pathogenic agents? Like for example, can biologists/chemists make drugs that inhibit certain enzymes? Is this an example of rational drug design? Also what about when someone has pain, can drugs be taken to like either act like enzymes and break down the neurotransmitters whilst diffusing through the synaptic cleft, or like bind on the post synaptic membrane receptors and block neurotransmitters from binding, hence no action potential is triggered to the adjacent neurone?

I feel like a doctor

Drugs (generally!) aren't enzymes - think of the difficulties of getting an enzyme to the place you want it in the body, while keeping it in an active form. There are some big counterexamples here, but they generally act in the gastrointestinal tract. That's not to say that drugs generally aren't proteins, but that's a whole different story...

Rational drug design 'works' by designing drugs that bind to proteins, based on knowledge (i.e. high-resolution, 3D structure) of the protein in question - often bound to the drugs in question. If you know the structure of the protein, you can design novel ligands that bind to the protein. These can act as activators ('agonists') or inactivators ('antagonists' or 'inverse agonists',) depending on the ligand in question. The examples you're given are usually by targeting a critical protein in a pathogen (i.e. the Rilenza/neuramidiase example.) There's been interest in targeting human proteins - either to inactivate them (in a situation when you've got too much protein activity,) or to activate them (where you want more.)

Obligatory - Rational drug design isn't actually as good as it's portrayed here. There's been a few 'success stories', but rational design is easier said then done.